Ecological Impact of Enhance Solar Ultraviolet Radiation on Phytoplankton at High Latitudes in the Arctic

增强太阳紫外线辐射对北极高纬度浮游植物的生态影响

• 批准号: 9907692
• 负责人: Osmund Holm-Hansen
• 金额: $ 31.16万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9907692&HistoricalAwards=false
• 关键词: Ecological; Impact; Enhance; Solar; Ultraviolet

9907692Holm-HansenRecent data shows that ozone concentrations in the stratosphere over the Northern Hemisphere during the spring period (March-May) are decreasing each succeeding year, continuing the decline that has been documented during the past decade. The magnitude of the depletion in atmospheric ozone is maximal at the higher latitudes in the Arctic, with progressively less depletion at lower latitudes. Depletion of this protective layer of ozone results in enhancing UV-B radiation (280-320 nm), with the influence of these shorter UV wavelengths incident upon the earth increasing exponentially with progressive loss of ozone. As the photons in the UV-B spectral region are highly energetic and their wavelengths overlap the absorption spectrum of many important cellular components (e.g., DNA), this enhanced UV-B radiation resulting from ozone depletion represents a significant threat to any living organism which is exposed to solar radiation. In this proposal we are concerned with the impact of solar UVR on Arctic marine phytoplankton, which constitute the base of the entire food web in the marine ecosystem.The project will be based at the Marine Biological Station of the University of Tromso, Norway, which is located at approximately 70 N and hence represents a high-latitude Arctic environment, but will also include ship-board studies in the Lofoten Islands and close to the ice edge in the northern Barents Sea. All experimental work will use either natural phytoplankton assemblages or unialgal phytoplankton cultures of ecologically relevant species in the Arctic food web. Both in situ incubations and temperature-controlled incubators with appropriate optical filters will be used to determine the impact of enhanced UV-B radiation (when column ozone values are low), 'normal' UV-B radiation, and UV-A radiation (320-400 nm) on structural damage to the genetic material in cells (DNA), on the loss of primary production, and on possible changes in species composition of the phytoplankton assemblages. Ancillary data will include the relationship between the magnitude of UV-induced cellular damage and the influence and total dose of UVR experienced by cells. Specific experiments will also determine whether or not the UV-induced cellular damage is reversible in time, and also the extent to which cells can mitigate the adverse effects of solar UVR by synthesis of UV-screening compounds. These studies will be supported by simultaneous measurements of relevant environmental factors, including incident spectral UVR and visible solar radiation with depth in the water column, and stability of the upper water column.The studies will be done in cooperation with personnel from the University of Tromso, who are also engaged in long-term monitoring of incident solar UVR in northern Norway. Students from both the USA and Norway will be active participants in the field work and in analysis of the data. The results from this cooperative project should provide a good data base to better our understanding of the possible impact of enhanced solar UVR on the floristic composition of the natural phytoplankton assemblages as well as on the rate of primary production. Such data will be important inputs to future modeling efforts to estimate the impact of progressive depletion of atmospheric ozone over the Arctic on the food resources available to higher trophic levels. As important fishery resources are located throughout the Arctic regions, such knowledge is also of importance in regard to economic and societal concerns.

9907692 Holm-Hansen最近的数据表明，春季（3月至5月）北方半球平流层中的臭氧浓度每年都在下降，延续了过去十年中记录的下降趋势。 北极高纬度地区的大气臭氧消耗量最大，低纬度地区的消耗量逐渐减少。 这一臭氧保护层的损耗导致UV-B辐射（280-320 nm）增强，随着臭氧的逐渐损耗，入射到地球上的这些较短紫外线波长的影响呈指数级增加。 由于UV-B光谱区域中的光子是高能量的，并且它们的波长与许多重要细胞组分的吸收光谱重叠（例如，DNA），这种由臭氧消耗引起的增强的UV-B辐射对暴露于太阳辐射的任何生物体构成重大威胁。 在这个建议中，我们关注的是太阳紫外线辐射对北极海洋浮游植物的影响，浮游植物构成了海洋生态系统中整个食物网的基础。该项目将设在挪威特罗姆瑟大学的海洋生物站，该站位于北纬70度左右，因此代表了高纬度的北极环境，但也将包括在罗弗敦群岛和靠近北方巴伦支海冰缘的船上研究。 所有实验工作都将使用北极食物网中与生态有关的物种的自然浮游植物组合或单藻浮游植物培养物。 将使用原位培养和带有适当滤光器的温控培养箱来确定增强的UV-B辐射的影响（当臭氧值低时），“正常”UV-B辐射和UV-A辐射（320-400 nm）对细胞中遗传物质（DNA）的结构损伤，对初级生产的损失，以及浮游植物组合的物种组成可能发生的变化。 辅助数据将包括紫外线诱导的细胞损伤的程度和细胞所经历的紫外线辐射的影响和总剂量之间的关系。 具体的实验还将确定紫外线诱导的细胞损伤是否及时可逆，以及细胞通过合成紫外线屏蔽化合物可以减轻太阳紫外线辐射的不利影响的程度。 这些研究将得到有关环境因素的同时测量的支持，包括入射光谱紫外线辐射和可见太阳辐射随水柱深度的变化以及上层水柱的稳定性，这些研究将与特罗姆瑟大学的人员合作进行，特罗姆瑟大学的人员也在长期监测挪威北方入射太阳紫外线辐射。 来自美国和挪威的学生将积极参与实地工作和数据分析。 这一合作项目的结果应提供一个良好的数据基础，以更好地了解增强的太阳紫外线辐射对自然浮游植物群落的植物区系组成以及对初级生产率的可能影响。 这些数据将成为未来模拟工作的重要投入，以估计北极上空大气臭氧的逐步消耗对较高营养水平的食物资源的影响。 由于重要的渔业资源分布在整个北极地区，这种知识对于经济和社会问题也很重要。